Plug for telephone-switchboards



(No Model.) I 'a C. E. lSCRIBNER & F. R. MCBERTY.'

PLUG FOR TELEPHONE SWITGHBGARDS. No. 574,281.

APatented Dec.- `29, 1896.

UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, AND FRANK R..MCBER'`Y, OF DOW- NERSGROVE, ILLINOIS, ASSIGNORS TO THE IVESTERN ELECTRIC COM- PANY, OFCHICAGO, ILLINOIS.

PLUG FIOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part 0f Letters Patent N0. 574,281, dated December29, 1896. Application filed May 31, 1894. Renewed .Tune 19, 1896. SerialNo. 596,221. (No model.)

To all whom, t may concern.-

Be it known that We, CHARLES E. SCRIB- NER, residing at Chicago, in thecounty of Cook, and FRANK R. MCBEETY, residing at Downers Grove, in thecounty of Du Page, State of Illinois, citizens of the United States,have invented a certain new and useful Improvement in Plugs forTelephone-Switchboards, (Case No. 355,) of which the following is afull, clear, concise, and exact description, reference being had to theaccompanying drawings, forming a part ot this specilication.

Our invention relates to connecting-plugs adapted to be used withspring-jacks of telephone-switchboards, being particularly applicable toconnecting-plugs having two or more separate insulated contact portions.Its object is to provide a plug of stronger and more durable structurethan heretofore used and our invention consists in certain details ofconstruction adapted to this end. l

Our invention is illustrated in the accompanying drawings, Ywhichrepresent a plug having three contact portions insulated from each otheradapted to make connection with three corresponding contact pieces of aspring-jack.

In Figure l of the drawings a plug having four contact-pieces isrepresented, two of which are arranged to make connection with twoinsulated contact parts of the plug and the remaining two to be crossedtogether by means of a third insulated portion of the plug. Fig. 2 is anenlarged longitudinal sectional view of our improved plug. Fig. 3 is asection of the same on line :t oo of Fig. 2. Fig. -l is a section online y y of the same figure. Fig. 5 is an elevation of certain parts ofthe plug, partially in section. Fig. 6 is a sectional view of the sameparts separated so as to disclose the order of assembling them. Fig. 7is an elevation of the plug with a portion of the shell removed to showthe manner of connecting the conducting-cords with the correspondingparts of the plug. Fig. S is a side elevation of the plug oi'approximately normal size.

The plug presents three separate contact portions to the Correspondingparts of the spring-jack-a nearly spherical tip d, a short cylindricalportion b, and a longer cylindrical portion c-the iirst two of which areadapted to make connection with the springs a. and b', respectively, andthe last to make contact with both the rings c and c2 of the springjack.The contact portion c of the plug is integral with the body or handle dof the plug. The body d is bored out through its entire length, the borebeing smaller within the portion c. Two connection-blocks c f arearranged within the body of the plug, insulated from its walls bysuitable concentric sleeves of hard rubber or other insulating material.

A tube g,preferably of steel,exten ds through the shank or contactportion c of the plug and is insulated therefrom by a surrounding sleeveh of hard rubber. Near its forward portion this tube g carries a shortcollar b, which is securely driven upon the tube and is separated fromthe shank c by an interposed washer 7l of insulating material. At itsforward extremity the tube is enlarged into a conical shape and carriesthe remaining contact-piece of the plug, the spherical tip a. This tiphas a conical hole init axially, lined with insulating material, thetaper of the perforation being the same as that of the cone-shapedextremity of the tube g. The tip ct is formed with a thin circular lipa2, which is designed to be turned or spun down in a lathe after theparts are assembled to cover the opening in the tip, as shown in Fig. 2.

A washer lo, of insulating material, is interposed between the tip a andthe collar b, and a similar washer l is also placed over the eX-trernity of the tube g. The connection with the tip a is carried to thebody of the plug by means of an insulated wire m, extending through thetubular aperture in the tube g. This wire is connected within the tip awith a small brass plate n, placed over the washer Z. rThe space abovethe washer n is filled with lead or soldero to insure perfect contactbetween the tip a and plate n.

Within the body of the plug the wire m IOO to the binding-post or blockc. For insuring contact with the rings c' and c2 when the plug isinserted in the spring-jack two springs p and p are provided in theshank c of the plug. These are constructed of wire and are arranged inlongitudinal slots in the shank c of the plug, each being securely heldby one extremity and being free to vibrate at its other extremity, thesprings being reversely arranged in respect to their points of rigidsupport. Thus the spring p is held at its lower extremity by the ringq,which is screwed upon the shank of the plug, while the spring p is notheld but is only limited in its play by this ring. The latter spring issimilarly secured by a ring o, also screwed upon the shank. The usualinclosin g shell or tubular cover S, oi' insulating material, isprovided, surrounding the greater part of the body of the plug.

In assembling the parts here described the conical insulating-tube isfirst placed over the tube g, around the conical extremity of the tube.Then the tip a is forced down into position over the same extremity ofthe tube. The insulating washer Z is then placed over the extremity oft-he tube g. The conductor on is inserted in the tube, bringing theplate n. into contact with the washer l, after which the solder o isplaced in the opening, heat being` employed, if desired, to insureperfect contact both with the plate ln and the tip a. The thin lip a2 isnow turned inward to complete the spherical shape of the tip a, wherebythe parts within the tapered opening of tip dare compressed firmlytogether and the tip is securely wedged upon the tube g. The washer 7cis next placed behind the tip a and the collar b is forced into placeiirmly against the washer. The tube g is finally inserted into theinsulated bore of the shank c and is screwed into place in block f, theconductor m being passed through the perforation in block fand screwedor soldered to its binding-post e.

The cord connections with the plug are made in the usual lnanner, oneconductor being connected with the binding-screw of block f and theother with the binding-screw of block c.

1f desired, the shank c maybe utilized as a third cord connection, thecorresponding conductor being secured in the usual way to the body ot'the plug.

Having thus described our invention, we claim as new and desire tosecure by Letters Patentl.`In a connectingplug the combination with atube forming or carrying one contact portion of the plug, of a secondcontact portion surrounding and secured upon a projecting portion ofsaid tube, and a wire extending from said second contact portion throughthe tube to the interior of the plug, substantially as described.

2. The combination in a connecting-plug, of a tube carrying onecontact-surface in an intermediate position, a second contact portionsupported upon and surrounding the proj ecting extremity of said tubebut insulated therefrom, and a conductor extending from said secondcontact portion through the tube to a suitable connecting-post withinthe body of the plug, substantially as described.

3. The combination with a tube of conducting material carrying a collaror sleeve forming one contact portion of a connectingplug, butprojecting beyond said collar, of a spherical tip constituting anothercontactpiece of the plug supported upon and surrounding the projectingextremity of the tube but insulated therefrom, and an insulatedconductor extending through the tube and connected with the sphericaltip, substantially as described.

4. In combination, a conducting-tube carrying a collar constituting onecontact-piece of the plug but projecting beyond the same, the projectionbeing enlarged at its outer extremity, a spherical tip constitutinganother contact-piece of the plug having an axial openin g correspondingin shape to the enlarged projection of the tube, insulating materialfilling the perforation in the tip about the tube, and an insulatedconductor connected with the tip and extending through the tube,substantially as described.

5. In combination, a tubular body or shank of a connecting-plug having aportion formed into a contact-piece for a spring-jack, a conducting-tubeextending longitudinally therein but insulated therefrom, a collarcarried upon said tube constituting a second contactpiece of the plug,said tube projecting beyond the collar, a spherical tip secured uponsaid projecting extremity of the tube but insulated therefrom, aconducting-wire connected with said tip and extending through said tube,and independent means for connecting with both the tube and theconducting-wire within the body of the plug, substantially as described.

C. The combination with the tube g, of the spherical tip a having thelip a2 formed thereon, said spherical tip being secured upon said tubebut insulated therefrom, and a conducting-wire connected with said tipwithin its central perforation, and extending through the tube, said lipa2 being finally turned down to close the opening in the tip,substantially as described.

7. The combination with the tube g carrying the collar b and having theenlarged projecting extremity, of the sleeve tof insulating materialsurrounding said extremity, the tip ce having an axial perforationcorresponding in form to said enlarged extremity and having the lip a2formed upon it, the insulatingwasher Z placed over the extremity of thetube g, said lip cbeing turned in to compress the enlarged portion ofsaid tube into the corresponding opening of the tip to secure the latterfirmly in place upon the tube, substantially as described.

8. In combination with the tip a having the lip a2 formed thereon, thetube g to which the IOO IIO

said tip is secured, the washer Z of insulating material covering theextremity of said tube, the conducting-plate nV forming the terminal ofconductor m, and the soft conducting material o placed over the plate n,whereby when the lip a2 is turned down the conducting material iscompressed and caused to make perfeet contact between the plate fn andthe tip a, substantially as described.

9. In a connecting-plug, the combination With a central conducting' stemforming a conduit, of two contact portions carried thereby and suitablyinsulated the one from the other and one insulated from such stem orconduit, and a Wire extending through such conduit from the contactinsulated from the stern for the purpose set forth.

In witness whereof we hereunto subscribe our names this 30th day ofApril, A. D. 1894:.

CHARLES E. SCRIBNER. FRANK R. MCBERTY. Vitnesses:

ELLA EDLER, LUoILE RUSSELL.

